Problem: $ { \left[\begin{array}{rrr}{-2} & {-2} & {-1} \\ {-1} & {4} & {3}\end{array}\right]+\left[\begin{array}{rrr}{3} & {1} & {4} \\ {-1} & {0} & {3}\end{array}\right] = {?} } $
Answer: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rrr}{-2}+{3} & {-2}+{1} & {-1}+{4} \\ {-1}+{-1} & {4}+{0} & {3}+{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{1} & {-1} & {3} \\ {-2} & {4} & {6}\end{array}\right]}$